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首页> 美国卫生研究院文献>Elsevier Sponsored Documents >Investigation of the oxygen exchange mechanism on Ptyttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path
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Investigation of the oxygen exchange mechanism on Ptyttria stabilized zirconia at intermediate temperatures: Surface path versus bulk path

机译：中间温度下氧化钇稳定氧化锆上氧交换机理的研究：表面路径与体积路径

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摘要

The oxygen exchange kinetics of platinum on yttria-stabilized zirconia (YSZ) was investigated by means of geometrically well-defined Pt microelectrodes. By variation of electrode size and temperature it was possible to separate two temperature regimes with different geometry dependencies of the polarization resistance. At higher temperatures (550–700 °C) an elementary step located close to the three phase boundary (TPB) with an activation energy of ∼1.6 eV was identified as rate limiting. At lower temperatures (300–400 °C) the rate limiting elementary step is related to the electrode area and exhibited a very low activation energy in the order of 0.2 eV. From these observations two parallel pathways for electrochemical oxygen exchange are concluded.The nature of these two elementary steps is discussed in terms of equivalent circuits. Two combinations of parallel rate limiting reaction steps are found to explain the observed geometry dependencies: (i) Diffusion through an impurity phase at the TPB in parallel to diffusion of oxygen through platinum – most likely along Pt grain boundaries – as area-related process. (ii) Co-limitation of oxygen diffusion along the Pt|YSZ interface and charge transfer at the interface with a short decay length of the corresponding transmission line (as TPB-related process) in parallel to oxygen diffusion through platinum.
机译：通过几何学上定义明确的Pt微电极研究了铂在氧化钇稳定的氧化锆（YSZ）上的氧交换动力学。通过改变电极尺寸和温度，可以分离两个温度范围，这两个温度范围具有不同的极化电阻几何依赖性。在较高温度（550-700°C）下，靠近三相边界（TPB）且活化能约为1.6 eV的基本步骤被确定为速率限制。在较低温度（300–400°C）下，限速基本步骤与电极面积有关，并显示出非常低的活化能，约为0.2 eV。从这些观察结果中得出了电化学氧交换的两个平行途径。这两个基本步骤的性质以等效电路的形式进行了讨论。发现了两种平行限速反应步骤的组合来解释观察到的几何形状依赖性：（i）与区域相关的过程，通过TPB杂质相的扩散与氧通过铂的扩散（最有可能沿Pt晶界）平行扩散。 （ii）沿着Pt | YSZ界面的氧扩散和与相应的传输线衰减长度较短的界面处的电荷转移的共限制（与TPB相关的过程）与通过铂的氧扩散平行。

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